• 한국도로학회논문집
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• 제15권2호
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• pp.47-55
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• 2013

PURPOSES : This study aimed to evaluate the feasibility of AASHTO86 design method for Bonded Concrete Overlay. METHODS : The Feasibility of AASHTO86 design method for Bonded Concrete Overlay is investigated based on the following study : i) Sensitivity analysis of designed service life of Bonded Concrete Overlay by major design input for AASHTO86 guide. ii) Comparison of actual Bonded Concrete Overlay life and predicted Bonded Concrete Overlay life by AASHTO86. iii) Finding the stress component influence the potential distress of Bonded Concrete Overlay based on 3-d FEM analysis. iv) Exploring the limitation of AASHTO86 in the aspect of design input. RESULTS : Sensitivity analysis showed that the condition of existing pavement significantly on the Bonded Concrete Overlay life. Also the overlay thickness affect the Bonded Concrete Overlay life. The comparison of actual Bonded Concrete Overlay life and predicted Bonded Concrete Overlay life showed relatively good agreement when the early distress sections are excluded in comparison. Bonding stress occurred at the interface may be larger than the bond strength used in the specification of Bonded Concrete Overlay construction. CONCLUSIONS : Bonded Concrete Overlay life predicted by the AASHTO86 may not be reliable. Number of points to improve the reliability in the design of Bonded Concrete Overlay are suggested in this study.

• 한국도로학회논문집
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• 제16권1호
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• pp.1-10
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• 2014

PURPOSES : This study aimed to evaluate the long-term performance of bonded concrete overlay in Korean Highway, and factors influencing the performances. METHODS : The evaluation for long-term performance of bonded concrete overlay is investigated based on the following study : i) The pavement distress of number of bonded concrete overlay sections in Korean highway are collected through field measurement, and PCI for each section is calculated. ii) Performance of LTPP data of bonded concrete overlay sections in U.S.A is analysed. And it is compared with bonded concrete overlay of Korean highway. iii) An analysis of the factors influencing to long-term performance of bonded concrete overlay is investigated. RESULTS : Performance analysis was confirmed that the overlay thickness was affecting significantly on the Bonded Concrete Overlay life. The comparison of LTPP data(U.S.A) and field measurement data(Korean) was showed. CONCLUSIONS : It was showed that the performance of Korean bonded concrete overlay is relatively lower than that of the bonded concrete overlay in U.S.A. The cause of lower performance can be explained by the lack of overlay thickness.

• 한국도로학회논문집
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• 제14권4호
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• pp.19-28
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• 2012

PURPOSES : Recently, the mechanistic-empirical overlay pavement design program that is linked with Korea Pavement Research Program (KPRP) has been developed. This paper focused on establishing the framework and developing the program for the asphalt overlay design over the existing asphalt concrete pavement. METHODS : The overlay pavement design program developed in this study was investigated to assess the sensitivity to various pavement conditions, such as the damage level and thickness of existing layers. In addition, the actual overlay design on currently performing pavement was carried out as a practical example. RESULTS : From the sensitivity analysis, it was found that the thickness and damage level of existing asphalt layer mostly affect the overlay design results. In addition, under the same condition, the overlay pavement would better perform in cold region. From the overlay design with the actual condition, it is noted that the overlay thickness varies depending on the given condition. CONCLUSIONS : Based on various evaluations, it was concluded that the overlay design program developed in this study is a reliable and reasonable tool to be used in the actual pavement design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.635-642
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• 1997

This research focused on the development of concrete overlay and test, which was conducted at 88 Highway 105k, 2 lanes of 290 m. The field application test consists of 6 cm and 10 cm bonded concrete overlay and 25 cm unbonded concrete overlay, using the slag cement for opening lanes for traffic early. The overlay were placed in a day. The whole period of traffic closing wes 8 day and it was reopened to traffic after concrete overlay has cured for 3 day. 5 cracks were founded when the field test section was investigated after 1 month, but all these may not make significant problems to overlay because these initiated and growed at the same line of repair section. The rideability and skid resistance become much better like in the new pavement after overlay. The structural capacity against deflection was much. which were verified by FWD(Falling Weight Deflectometer). The field test section is being used in a good condition and the results of field application and pavement performance analysis are encouraging. This rehabilitation methods may be adopted in Korea after a more field performance verifications.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.88-93
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• 2008

Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a preemptive weld overlay(PWOL). PWOL was good for distribution of residual stress of dissimilar metal weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR.

• 대한전자공학회논문지TC
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• 제47권10호
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• pp.57-66
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• 2010

오늘날 인터넷 및 IP 기술의 발달에 의해 다양한 통신 형태와 응용 서비스가 제공되고 있다. 인터넷 기반 서비스 제공을 위한 기술로 각광을 받고 있는 P2PSIP overlay 기술과 NGN의 진화에서 채용된 IMS 네트워크와의 상호접속을 통해 두 기술의 서비스 영역 확대를 기대할 수 있다. 따라서 본 논문에서는 P2PSIP overlay와 IMS 네트워크를 상호접속 시켜 서비스의 확장이 가능한 방법에 대해 연구한다. 특히 상호접속 방법으로 가입자 가입 유형별로 적용이 가능한 구조를 나타내고, 세션 설정 시간 관점에서 트래픽 모델과 지연 특성을 분석한다. 그리고 제안 방식의 특성 분석 및 평가를 위해 시뮬레이션 모델을 통해 세션 설정지연 시간을 분석하고, 가입자 가입 유형별 적절한 상호접속 방법을 제시한다. 그 결과 P2PSIP overlay 전용 가입자인 경우는 gateway AS를 통해 IMS에 접속하는 구조 그리고 P2PSIP overlay와 IMS 네트워크에 동시 가입한 경우는 I-CSCF을 통해 접속하는 구조가 세션 설정 지연 특성 관점에서 가장 우수함을 분명히 한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.260-262
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• 2007

In nuclear power plants, residual stress of dissimilar metal weld propagates cracks in the weld metal which is susceptible to stress corrosion cracking. Overlay welding is a process widely used to mitigate residual stress replacing inside tensile stress by compressing stress. The purpose of this paper is to predict the effect of weld overlay by finite element analysis.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2012년도 한국컴퓨터종합학술대회논문집 Vol.39 No.1(D)
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• pp.190-192
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• 2012

In this paper, we present theoretical queuing analysis for hybrid overlay/underlay Cognitive Radio (CR) system by applying M/M/1 queuing model where the rate of arrival and the service capacity are subject to Poisson alterations. Numerical results are used to prove a high degree of accuracy for the derived expressions. The result can be used as a benchmark to evaluate the performance of a hybrid overlay/underlay CR system.

• 한국도로학회논문집
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• 제18권3호
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• pp.33-45
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• 2016

PURPOSES : Concrete pavement has been used in the construction of the Jungbu expressway in 1987. More than 60% of the pavement on the expressway is currently made of concrete, but most has been used far beyond their design life. Pavement life has been extended through routine maintenance or overlay. However, the structural capacity of the pavement has reached its limit, and extensive rehabilitation/reconstruction with long time traffic blocking should be considered. The three following issues on concrete rehabilitation/reconstruction will be discussed: (1) economic comparison of asphalt inlay and asphalt overlay, (2) economic comparison preventive overlay on a section which is currently good and routine overlay on the section which will be poor, and (3) economic analysis of early-strength concrete when it is used in concrete reconstruction. METHODS : First, various life cycle cost analysis tools were compared, and the proper tool for the extensive rehabilitation/reconstruction was selected. Second, a sensitivity analysis of the selected tool was performed to find the influential input variables, which should be carefully selected in the analysis. Third, three case studies, which can be issues in the rehabilitation/reconstruction of the expressway concrete pavement in Korea, were performed. RESULTS : Asphalt overlay without milling the deteriorated concrete showed 18~25% lower life cycle cost than the current asphalt inlay with milling. The good current preventive overlay on the section was economically justified within the scope of this study. The construction cost limit of the early strength concrete was suggested to be economical for 1, 3, and 7 days of construction alternative opening. CONCLUSIONS : CA4PRS was a viable tool for comparing various rehabilitation/reconstruction issue alternatives. Several concrete issues associated with the rehabilitation/reconstruction of the deteriorated concrete pavement were discussed as mentioned above.

• 한국도로학회논문집
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• 제19권6호
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• pp.75-81
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• 2017

PURPOSES : So far, aged cement concrete pavement on express highways has been rehabilitated mainly with asphalt concrete inlay. However, potholes were the major problem, and they shortened the life of the inlay mainly owing to the poor drainage of water once it infiltrated the interface of the concrete and asphalt. The purpose of this study is to compare the performance and economic efficiency of asphalt overlay and inlay. METHODS : Overlay and inlay were compared through accelerated pavement testing, and a life-cycle cost analysis was conducted in this study using the CA4PRS program. RESULTS and CONCLUSIONS : It was found from accelerated pavement testing that the overlay exhibited reflective crack resistance that was more than twice as effective as that of inlay. The total cost (construction cost + user cost) within the analysis period (20 years) of the overlay was 37% lower than that of the inlay.